1. Field of the Invention
The present invention relates to a barcode module for automated data storage libraries. More particularly, the present invention relates to a barcode module capable of being manipulated by a picker and easily retrofitted to existing data storage libraries
2. Description of Related Art
An automated data storage library or autochanger, otherwise known as a data jukebox, allows a host computer to access data on a large number of storage media, such as magneto-optical cartridges or CD-ROMs. A data jukebox typically includes a CCU (Central Control Unit), a picker, drives, a mailbox, and multiple slots to keep the storage media. The CCU receives commands from the host computer and processes the commands to control the picker, the drives, and the mailbox. The picker physically moves the storage media between the drives, the mailbox, and the slots. The drives exchange data with the storage media. The mailbox allows a user to insert or remove storage media into and from the data jukebox.
The CCU controls the motors and sensors required to operate the picker, the drives, the mailbox, and other components. A typical CCU encompasses all hardware and software functions required for these motors and sensors. Host interface control and low-level motion control are all contained in the same monolithic CCU, which often takes the form of a large printed circuit board.
By the nature of motion control, high frequency and high current signals must route through portions of this main board on their way to the motors they control. This places these signals in close proximity to the data paths over which user data travels. Special care must be exercised in the design of such a circuit to minimize or eliminate interference between these two separate functions. Isolation of these regions of the board requires expensive construction of the board itself, or the placement of the high current motor signals on an entirely separate board, which increases complexity and cost. When the motor drive signals are sent to the motors, they must travel across long cables before reaching their destination. These long cables act as an antenna for the transmission of electromagnetic interference, which can be picked up by the sensitive data cables attached to the internal data drives. Moreover, these long cables are frequently specialized and expensive.
In addition, motors are often equipped with incremental encoders for determining their position. The signals from these encoders are typically weak and very high frequency. The cables over which these signals travel back to the control board are susceptible to the noise generated by the high current motor drive signals. This kind of interference with the encoder signals may cause a motor controller to lose the correct position of the motor, which in turn causes error in servo positioning. This can eventually lead to failure of the robotics mechanism to properly handle data cartridges.
The wiring required to carry a multitude of motor control and encoder signals over a long distance through the jukebox is specialized and expensive. For example, custom-fabricated, application-specific flexible circuits must be designed and manufactured for the picker. The complexity and cost of the wiring and interconnects also increases with picker complexity. Furthermore, a significant portion of manufacturing effort is devoted into connecting and checking that each and every connection has been properly made.
Typically, media is inserted through the mailbox, which stores the location of each media. However, loading of the jukebox through the mailbox is slow, as only one piece of media can be loaded at a time. Also, when the cabinet of the jukebox is opened and the slots accessed directly, the location of media may be shuffled and an inventory process must be performed.
To inventory the contents of a jukebox, a machine readable identification tag may be placed on the media. For example, a barcode may be placed on the edge of the media. This allows rapid inventory of the media in a jukebox.
Current barcode readers are integrated with the picker. This means older jukeboxes must be retrofitted in order to take advantage of the barcode reading capabilities. Also, to service the barcode reader means having to service the entire picker.
What is needed is a data jukebox which is less susceptible to electromagnetic interference than current jukeboxes. What is also needed is a data jukebox which has simpler wiring between components than current jukeboxes.
What is needed is a barcode module which can be used with existing jukeboxes and provide barcode functionality.